(1) Field of the Invention
The present invention relates to the manufacture of an inflatable traction kite as well as its system for managing the traction power, the direction and the transient manoeuvres.
This invention is related to the field of the sail traction of aquatic boards, and other beach vehicles, boats as well as of skiers, surfers and adapted road vehicles.
(2) Description of the Prior Art
It is known to use two types of inflatable traction kites:                the so-called flat kites, which generally have a ratio between the flat wing span, i.e. the distance separating the two ends of the kite, and the in-flight wing span, i.e. the width of the kite during the flight, which is lower than about 1.5. Their control occurs by means of a complex rigger system arranged along the wing span.        the so-called kites the ratio between the flat and the in-flight wing span of which is larger than about 1.5, and which are of the type referred to as “C-shape” or “C-kite”. These kites have the characteristic shape of a negative dihedron, i.e. a regular and deep arch. They have the peculiarity of being able to fly and being controlled by riggers located at its ends.        
These riggers are generally four in total and of a length of about twenty meters, the first two being located at the front ends of the kite are defined as bearing riggers and the other two riggers are located at the rear of the ends and used for managing the direction and the trim.
The bearing riggers are connected to the pilot by means of a harness and the direction riggers are hooked in on both sides of a sliding bar on a rigger uniting the bearing riggers over the last meter at the level of the pilot.
The bearing riggers receive the largest portion of the aerodynamic load, they are generally located slightly forward of the resultant of the aerodynamic forces (RAF), in order to confer to the kite a pitching torque that permits to transfer part of these forces to the rear riggers, which therefore ensure the control of the trim by the pilot.
When the rear riggers are actuated asymmetrically, they induce a deformation of the kite, which, by generating a differential aerodynamic drag, permits to control the direction of the kite.
This control system is generally combined with other riggers located on the leading edge and that enter into operation to assist managing the phases out of flight, take-off or to ensure maintaining the kite in the vicinity of the pilot in the event the control bar is released or to assist controlling the trim.
These systems considerably complicate the management of the kite both in flight and on the ground, on the other hand, the management of a high number of riggers is a source of non-negligible and potentially dangerous errors.
The wing profile of the conventional self-bearing kites implies that the bearing riggers and the control riggers are not far separated from the position of the resultant of the aerodynamic forces. The wing profile of these kites has therefore a regular curvature of the leading edge and the trailing edge towards an equilibrium point located slightly behind the bearing riggers and before the riggers for managing the direction.
Since this kite shape is stable only when there exists a sufficient lift for maintaining the kite during the flight, the anchoring points of the bearing riggers should be placed relatively close to the axis of equilibrium, thus inducing a limit for the slack capacity beyond a minimum incidence after which the kite could no longer ensure its lift and would nose dive onto the ground without the pilot being able to ensure its control.
This minimum incidence is potentially dangerous in the event of an increase of wind, because the force thus generated can cause a loss of control by the pilot.
On the other hand, when the kite is in slacked position, the arrangement at the ends of the kite of the bearing riggers induces a decrease of the wing span and a reduction of the angle of incidence of the last third of the kite, thus cancelling its directional role.
Regaining the control of the direction implies a recovery of incidence of the entire kite, which is potentially dangerous in case of an increase of wind.
The multiple systems of riggers presently available do not provide any suitable solution for these problems, therefore the present invention is aimed at coping with this lack.